Published data regarding asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), L-arginine (L-ARG) and nitric oxide fraction in exhaled air (FeNO) in pediatric bronchial asthma are limited. Many question remain open about plasma concentration of these substances. The aim of this study is to evaluate ADMA, SDMA, L-ARG and FeNO concentration in allergic pediatric mild asthmatic patients in respect to healthy subjects. In this case-control study 60 children (50 asthmatics and 10 healthy) underwent a complete clinical visit, baseline respiratory function, allergy tests and biochemical analyses. The statistical significance of the different concentrations between the two groups were studied using one-way analysis of variance (ANOVA). A p value less than 0.05 was considered statistically significant. The mean plasma ADMA (0.58 vs 0.68 micromol/L), SDMA (0.40 vs 0.45 micromol/L) and L-ARG (52.2 vs 74.13 micromol/L) concentration were significantly lower (p less than 0.001) in the asthmatic patients in respect to healthy subjects (control group). The concentration of FeNO was significantly higher in the asthmatic subjects in respect to the control group (9.18 vs 4.2 micromol/L; p less than 0.001). Low plasma concentrations of ADMA, SDMA, L-ARG and high concentration of FeNO are associated with bronchial asthma and indicate an important role in airway disease through NO metabolism.